In the following discussion, certain articles and methods are described for background and introductory purposes. Nothing contained herein is to be construed as an “admission” of prior art. Applicant expressly reserves the right to demonstrate, where appropriate, that the articles and methods referenced herein do not constitute prior art under the applicable statutory provisions.
Methods are available for the analysis of biological media, such as blood. These can be broadly classified into optical fluorescence, optical phase, electrochemical, and magnetic techniques. For example, a representative optical fluorescence method is Enzyme Linked ImmunoSorbent Assay (ELISA). Surface Plasmon Resonance (SPR) is a commonly used optical phase method. Electrochemical methods such as Differential Pulse Voltammetry (DPV) and magnetic methods such as MAgnetic Relaxation ImmunoAssay (MARIA) can also be used.
Typically the above methods contain a sensing element that requires either regeneration or replacement. Regeneration often involves treatment with a series of reagents, precluding usage outside of a controlled laboratory environment, and requiring careful consideration of calibration issues. Furthermore, the supporting hardware can be bulky and expensive. Replacement may be better suited for a non-laboratory environment (such as residential use), but recurrent cost considerations can be prohibitive to wide-spread usage.
The above methods also often exhibit a vulnerability to non-specific binding that interferes with accurate measurement of analyte concentration. Complex biological samples contain a plethora of molecules that may interact, even weakly, with a receptor intended to bind with an analyte molecule of interest. This may falsely overstate the measure of analyte concentration by proxy behavior, or falsely understate the measure of analyte concentration by blocking the binding of the analyte.
Because of the above disadvantages, there is a need for new methods, compositions, and/or systems that have widespread applicability for portable, inexpensive, reliable, and adaptable analysis of complex biological samples, such as blood samples for disease diagnosis.